The present invention relates generally to crop harvesting and conditioning machines. More specifically, the invention relates to means for driving the crop conditioning rolls of such a machine so that they remain properly indexed one with the other while at the same time allowing the axial spacing between rolls to be self-adjusting to accommodate for variations in the quantity of crop cuttings passing between the rolls. Throughout a wide range of roll spacing, tension in the drive chain is maintained at a uniform value. Further, by placing the axis of the power transmission at the pivot point the header suspension mechanism control of the height of the cutter bar above ground is maintained both during field use and while in the transport mode.
Combination mower and crop conditioner machines have been disclosed in the past. Examples of prior art configurations are the machines covered by U.S. Pats. Nos. 3,300,953; 3,309,850; 3,729,907; 3,747,310 and 3,797,207. U.S. Pat. No. 3,300,953 to Glass deals with drive means for a hay harvesting machine having a mower, a crop gathering reel and a pair of crop conditioning rolls. U.S. Pat. No. 3,309,850 to Glass et al. shows means for biasing a movable hay conditioning roll so that it adjusts to provide a proper roll-to-roll pressure in compensation for different crop conditions. U.S. Pat. No. 3,729,907 to Burrough et al. covers a power drive train for a mower-conditioner which is said to have improved simplicity over the previous art. The hay conditioner drive mechanism disclosed by Calder in U.S. Pat. No. 3,747,310 shows one approach for allowing one conditioning roll to move toward and away from the other roll to accommodate the varying thickness of the crop passing between the rolls. U.S. Pat. No. 3,797,207 to Sawyer et al. deals with the frame construction and header suspension mechanism of a mower-conditioner machine.
While the prior art mover-conditioner machines are generally satisfactory, none has the features of my invention. The rolls of my invention remain properly indexed and are driven in timed synchronism throughout a substantial range of spacing, while uniform drive-chain tension is maintained. The need for a simple subsystem to perform this function arises because the upper roll is made of a resilient material having a multiplicity of circumferentially spaced ribs. The lower roll (journaled on a fixed axis in the sidewall ends of the frame) is made of a rigid material with a rib formation that complements that of the upper roll. In operation the two rolls must register rib-to-rib at all times and drive chain tension maintained so that an intermittent crushing action is exerted on the stalks of crops passing between the rolls. U.S. Pat. application Ser. No. 637,190, filed Dec. 3, 1975, entitled "Crop Conditioner Roll Structure", and assigned to the same assignee as this invention, describes the roll configuration.
In driving a pair of rolls which must always register rib-to-rib, it has been discovered that the arrangement of the power drive train relative to the pivot axis of the movable roll becomes an important factor. My invention provides a solution for this problem and embodiments thereof are capable of being readily adjusted to provide adequate roll pressure under all crop conditions.
The power drive arrangement also allows for a novel arrangement of the suspension mechanism. Various frame and suspension configurations have been employed in the past. U.S. Pat. No. 3,797,207 and the references cited therein typify what has already been done. My invention presents a solution to the problem of transmission positioning which results in a simpler and hence more reliable power drive train than previously existed.